fix: performance-no-automatic-move in GetBundleResourcePath()

remove `const` from request_relative_path.

Warning fixed by this commit:

electron/shell/browser/extensions/electron_extensions_browser_client.cc:187:10: warning: constness of 'request_relative_path' prevents automatic move [performance-no-automatic-move]

shell/browser/extensions/electron_extensions_browser_client.cc

@@ -174,7 +174,7 @@ base::FilePath ElectronExtensionsBrowserClient::GetBundleResourcePath(
   if (!chrome_resources_path.IsParent(extension_resources_path))
     return base::FilePath();
 
-  const base::FilePath request_relative_path =
+  base::FilePath request_relative_path =
       extensions::file_util::ExtensionURLToRelativeFilePath(request.url);
   if (!ExtensionsBrowserClient::Get()
            ->GetComponentExtensionResourceManager()